Welding flux



United States Patent Ofi ice 7 7 3,192,076 Patented June 29, 19653,192,076 WELDING FLUX John T. Ballass and Bernard J. Freedman, Groton,Conn, assignors to General Dynamics Corporation, New York, N.Y., acorporation of Delaware No Drawing. Filed July 28, 1961, Ser. No.127,485 4 Claims. (Cl. 148-26) This application is acontinuation-in-part of our application Serial No. 47,369, filed August4, 1960, now abandoned, for Welding Flux.

This invention relates to welding flux and, in particular, to a weldingflux suitable for use in welding of low alloy high strength steels.

Welding fluxes are indispensable in providing a high quality weldment,their nature and manner of use depending upon the type of metal beingjoined by the weld and upon the welding process used. Regardless of.these variables, the usual purpose of a welding flux is the formationof a protective covering for the metal at the welding site to preventoxidation and/ or other undesirable changes inthemetal during welding.

The submerged arc welding process uses a blanket of molten flux toshield the welding electrode and molten deposited metal from theatmosphere. In submerged arc welding of low alloy high strength steelsemploying the welding wire described and claimed in our applicationSerial No. 850,107, filed November 2, 1959, for Low Alloy Steel, nowabandoned, and its continuation-in-part application Serial No. 63,971,filed October 21, 1960, now U.S. Patent No. 3,115,406, for Low AlloySteel Welding Wire, and using a commercial neutral flux similar to thatdisclosed in U.S. Patent No. 2,751,478, and obtainable from Linde AirProducts as neutral flux Grade 80, it was found that the strengthproperties of the weldments were not entirely satisfactory with heatinputs suflicient to provide economic welding speeds.

The present invention relates to a welding flux useful in the welding oflow alloy high strength steels which provides deposited weld metalhaving mechanical properwith other welding processes such as theElectro-Slag method.

The welding flux of the present invention contains by weight 2 to 24%lithium fluoride (LiF), 5 to 20% calcium fluoride (CaF to 30% aluminumoxide (A1 0 0 to 20% manganese oxide (MnO), and the remainder silicondioxide (SiO and. calcium oxide (CaO), the latter two ingredients beingpresent in amounts within the range of proportions by weight of Si0 toCaO of from about 4:1 to about 1:1.

While Welding fluxes within the recited ranges of materials have beenfound satisfactory, the preferred ranges of flux constituents include byweight 6 to 12% lithium fluoride, to 12% calcium fluoride, 5 to 15%aluminum oxide, 5 to manganese oxide, and the remainder silicon dioxideand calcium oxide in the approximate Weight ratio of two parts ofsilicon dioxide to one part of calcium oxide.

The raw materials used in preparing the fluxes of this invention arepreferably of the usual commercial purity although incidental impuritiesdo not affect the welding appreciably. The raw materials are preferablyof a particle size such that 100% thereof will pass through a -50 meshscreen. In preparing the fluxes of this invention, silica, lime,manganous oxide, alumina, fluorspar, and lithium fluoride are combinedin preselected proportions and mixed in the dry state to obtain auniform homogeneous mixture. The silica may be of a mineral gradecontaining at least Si0 and a 5% maximum of aluminum. The lime may be ofa commercial grade and contain at least 92% CaO after drying at 2000 F.It may also contain a maximum of 1.5% magnesium and 2% aluminum. Themanganous oxide may be of a commercial grade containing a minimum Mncontent of 45%, a maximum Fe content of 8%, a maximum Al content of 5%,a 1% maximum Zn, As, Pb and 2% maximum of Ba.

The alumina is calcined, of a commercial grade, and contains 99% A1 0after drying at 2000" F. The fluorspar is of mineral grade, containingat least of CaF and the lithium fluoride is of a technical gradecontaining at least 99.5% Li as LiF. In addition to the above, from 0 to10% by weight of magnesium oxide (MgO) can be tolerated in the flux. Themagnesium oxide (MgO) is calcined, of a commercial grade, and contains99.65%

MgO after drying at 2000 F.

The Welding flux of this invention may be made by any of theconventional methods employed in the art, i.e., either the fusion, thesintering, or the bonding methods.

In the fusion technique, the constituents are mechanically mixed witheach other and the mixture placed in a graphite crucible and heated atabout 2400 to 2600 F. until it melts. -After heating the molten mass forabout 20 more minutes to insure complete fusion, it is quenched to roomtemperature and subsequently ground and crushed. The granules of fluxcan be stored for an indefinite period of time without the adsorption ofmoisture.

The flux of this invention may also be prepared according to a sinteringtechnique in which the mechanical mixture of constituents is heated inan oven at 1650 F. for 1 /2 hours. The mass is then cooled, crushed,screened and used in the same manner as the fused materials.

When the flux of this invention is prepared according to a bondingtechnique, the mixture of constituents is combined with Water glass in aratio of one part of water glass to three parts of the flux mixture.This mass is then heated to 900 F. for three hours, crushed, screenedand then employed in the usual manner. Of the three methods describedfor preparing the flux of this invention, the fusion technique ispreferred.

Table 1 lists a number of specific examples of the inventive weldingflux prepared by the fusion method which have provided high strengthWeldmerits in a low alloy high strength steels at an economicallyadvantageous welding speed. The analysis was determined on theconstituent mixture prior to fusion. Fluxes X and Yare control samplescontaining no Li'F, and are inserted for purposes of comparison.

TABLE 1 Analysis of flux in percentage by weight Flux LiF CaFz A1203 MnOMgO SiO: CaO

3 4.- HY-80 steel, which is an exemplary high strength low Element:Continued- Percentage by weight alloy 'steel having a yield strengthbetween 80,000 and Chromium 0.15 max. 100,000 p.s.i., has the followingchemical composition: Molybdenum 0.15-0.25.

. Copper 0.60-0.90plus 0.15 max. Percentage by as flashed coating.Element: weight Zirconium 0.15-0.25. Carbon .22. max. Aluminum 0.04 max.

Manganese .1 to .4 Phosphorus 035 In the experiments of Table 3designated as fluxes L Sulphur '04 max. through 0, plates of HY-80 steelwere welded using a Silicon 5 Welding wire 7 in diameter in accordancewith the Nickel 2 to 275 above-mentioned application Serial No. 850,107,now Chromium abandoned, and its copending continuation-impart appli-Molybdenum 23 to cation Serial No. 63,971, and having the following com-15 position:

The complete specifications of HY-SO steel may be Pfir'celltage y foundin U.S. Government Specification MIL-S-162l6D Element: Wfilgh't (NAVY)Carbon .093

In certain of the experiments summarized in Tables 2 Manganese and 3,namely Grade 80-1, Grade 80-2, Grade 80- 3, and Phosphorus fluxes x, Y,A-K and P, plates of I-IY-SO steel were ulp welded using a welding wire& in diameter in accordslllcofl ance with the above-mentionedapplication Serial No. Nlcke1 850,107, now abandoned, and its copendingcontinu-ation- Chromium in-par-t application Serial No. 63,971, havingthe following Molybdenum composition: PPP I 50 Percentage byZ'lI'COXllllIl'l .08 Element: weight Carbon 0.12 max. The mechanicalproperties of HY-80 steel plates welded Manganese 1.30-1.60. 0 With theexemplary welding fluxes set forth in Table 1 Phosphorus 0.015 max. andthe welding wiresdescribed above are listed in Tables Sulphur 0.015 max.2 and 3. Also listed for purposes of comparison are the Silicon 0.20max. strength characteristics of three and two plates welded Nickel0.75-1.00. with a flux lacking lithium fluoride.

TABLE 2 Percent elon- Charpy V-Notch impact toughness Plate PercentTensile Yield gation, based Percent (impact energy ft.-1b.) Welding fluxthickness LiF in Arc strength strength on 4D where reduction (in) fluxvoltage p.s.i.). 2% 0E- D=test in areaset (p.s.i.) bar Room 0 F. 60 F.-100 1*.

diameter temp.

Grade 80-1 1 *0 27 107,000 82,200 20 52.3 51 N.D. 29 23 Grade 80-2.-

2 *0 30 105,000 81,000 28.6 37 23 14 N.D. Grade 80-3.. 2 *0 111,50082,000 17.8 38 35 21 10 1 0 27 101, 000 ,100 20 50 5 39 34 21 N.D. 1 027 109, 000 87, 400 18. 0 40 30 24 20 N.D. 1 4 27 98,000 84,400 22.8 240 38 27 21 1 6 27 101,000 87,500 22. 2 0 47 40 27 19 1 7.7 27 102,00090, 500 20.7 54 9 88 86 58 41 1 7.7 27 96, 500 84, 700 23.6 59 3 50 5941 27 1 11.5 27 104,000 90, 200 19.3 53 8 76 71 50 32 1 8 27 105,00093,100 22.8 59 1 80 53 47 1 11.5 27 104,000 88,000 22.8 58 4 79 70 49 381 12. 5 27 115, 000 84, 800 18. 0 55 45 37 20 2 18. 2 30 108,000 89,50018 42 4 00 40 20 22 2 7. 7 35 101, 500 91, 000 22. 1 58 55 58 41 30 1 2427 104,0 83,500 19.3 50 78 70 52 32 urade TABLE 3 Percent Charpy V-Notchimpact toughness (impact energy Ft.-lb.) Tensile Yield elongation,Percent Welding flux Percent strength strength, based on 4D reductionLiF influx (p.s.i.) .2% otlsct where D= in area Room (p.s.i.') test barTemp. 0 F. -60 F. -80 F. F.

diameter Flux K 12 101,000 85,200 22.9 57. 5 71 55 43 N.D 27 Flux L 12113, 900 90, 000 19. 4 54 76 47 34 25 N.D. Flux M 12 113, 400 90, 00022. 1 50 73 60 3 1 31 N.D. Flux N 12 116, 300 03, 000 20. 0 54 64 43 2525 N.D. Flux O. 12 122, 300 86, 100 20. 7 58 74 45 25 N.D. Flux P 11. 5101, 000 88, 000 22. 8 53 64 55 34 N.D 27

N,D --Data not determined.

In Table 3 above, the plate thickness was 1 inch and the arc voltage was27 in each instance.

The data shown in Tables 2 and 3 were obtained from welds made with theabove-described diameter welding wires and a heat input of about 40,000joules per inch provided by direct current reverse polarity are currentsof from 550 to 800 amperes with the electrode moving along the weldjoint from 16.5 to 22 inches per minute. The welding wire electrodeswere bare metal and the granulated flux was supplied to the Weld insuflicient quantities by gravity feed concentric with the weldin gelectrode. However, the flux could be coated on the electrodes, ifdesired.

It is apparent from Tables 2 and 3 that the inventive Welding fluxescontaining from 2 to 24% lithium fluoride and the remaining specifiedingredients provide weldments superior to those obtained usingconventional prior art fluxes. Note particularly the marked increase innotch toughness of welds made with the lithium fluoride flux ascontrasted with those using the Grade 80 flux or fluxes X and Y.

From the data, it is evident that the preferred lithium fluoride rangeis from 6 to 12% and flux D has provided excellent welds with aneconomic quantity of 7% lithium fluoride. However, both smaller andlarger quantities of lithium fluoride also provide superior welds.

Although the usefulness of the flux of this invention has been describedin terms of a submerged welding technique, it is recognized that theflux may be used in other welding methods. For example, the flux of thisinvention can be used as the flux core of a hollow tubular welding wire.Further, the addition of certain materials to the flux core which form avapor shield over the welding site is contemplated, such as in themethod described in the article by R. A. Wilson in Welding Journal, vol.40, No. l, January 1961. Furthermore, the flux of this invention can bemixed with metallic particles having, for example, the same analysis asthe welding wire or as the steel being joined. This type of flux mixtureis well known in the art, and because it is attracted to the weldingsite by magnetism in electric welding, it can be used in situationswhere a gravity feed of flux cannot be provided.

It will be understood that the above-described ernbodiments of theinvention are illustrative only and modifications thereof will occur tothose skilled in the art. Therefore, the invention is not to be limitedto the particular examples described herein but is to be defined by theappended claims.

We claim:

1. A welding flux consisting essentially of, by weight, about 2 to 24%lithium fluoride, 5 to 20% calcium fluoride, up to 30% aluminum oxide,up to 20% manganese oxide, up to 10% magnesium oxide, and the balancebeing essentially silicon dioxide and calcium oxide in the approximateWeight ratio of silicon dioxide to calcium oxide within the range ofabout 4:1 to about 1:1.

2. A welding flux consisting essentially of, by weight, about 6 to 12%lithium fluoride, 5 to 12% calcium fluoride, 5 to 15% aluminum oxide, 5to 10% manganese oxide, and the balance being essentially silicondioxide and calcium oxide in the approximate ratio of two parts ofsilicon dioxide to one part of calcium oxide.

3. A welding flux consisting essentially of metal particles and the fluxdefined in claim 1.

4. A welding flux consisting essentially of, by weight, about 11.5%lithium fluoride, 11.5% calcium fluoride, 15.4% aluminum oxide, 7.7%manganese oxide, 34.7% silicon dioxide, and 19.2% calcium oxide.

References Cited by the Examiner UNITED STATES PATENTS 2,043,960 6/36Jones et al. -14826 3,023,133 2/62 Lewis et al. 148-26 3,023,302 2/62Kennedy et a1. 14826 3,076,735 2/ 63 Sharav et al 148-26 DAVID L. RECK,Primary Examiner.

RAY K. WINDHAM, WINSTON A. DOUGLAS,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,192,076 June 29, 1965 John T. Ballass et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, line 14, for "23 to .35" read .23 to .35

Signed and sealed this 30th day of November 1965.

(SEAL) Allest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A WELDING FLUX CONSISTING ESSENTIALLY OF, BY WEIGHT, ABOUT 2 TO 24%LITHIUM FLUORIDE, 5 TO 20% CALCIUM FLUORIDE, UP TO 30% ALUMINUM OXIDE,UP TO 50% MANGANESE OXIDE, UP TO 40% MAGNESIUM OXIDE, AND THE BALANCEBEING ESSENTIALLY SILICON DIOXIDE AND CALCIUM OCIDE IN THE APPROXIMATEWEIGHT RATIO OF SILICON DIOXIDE TO CALCIUM OXIDE WITHIN THE RANGE OFABOUT 4:1 TO ABOUT 1:1.